Crude oils of different origins can contain varying levels of contaminants within the feed. In some instances, the contaminant levels in a crude oil can be characteristic of the regional source of the crude oil. For example, crude oils extracted from sources in California tend to have high levels of nitrogen contamination. When such a California crude enters a refinery, the high nitrogen levels may impact multiple processes within a refinery.
Conventionally, it is known that the amount of nitrogen in a feed can negatively impact the catalytic activity in hydrotreating processes. This can lead to difficulties, as hydrotreatment is one of the most prevalent processes used for removal of nitrogen.
U.S. Pat. Nos. 6,162,350 and 7,513,989 describe a bulk metal catalyst composition that can be used for various types of hydroprocessing. Suitable feedstocks are described as including feeds that contain “substantial” amounts of nitrogen. A feed having a nitrogen content of at least 10 wppm is noted as an example of a feed containing a “substantial” amount of nitrogen. It is also noted that feeds having greater than 500 wppm of nitrogen can be treated. Experimental examples are also described where a vacuum gas oil feed having a nitrogen content of 858 wppm is hydrocracking in the presence of a bulk metal catalyst.
U.S. Pat. No. 7,597,795 describes a method for hydrotreating a lubricant oil basestock using a supported hydrotreating catalyst followed by a bulk metal catalyst. The feedstock for the process is described as having a nitrogen content of up to 0.2 wt %. Examples are provided of hydrotreating vacuum gas oil feeds with nitrogen contents as high as 1573 wppm.